Vapor-electric device



Patented Nov. 4, 1952 VAPOR-ELECTRIC DEVICE Gerhard Lewin, Maplewood, N.J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa.,a corporation of Pennsylvania Application October 14, 1950, Serial No.190,141

7 Claims. 1

The invention relates to vapor-electric devices such as are generallyknown as ignitrons.

Attempts have heretofore been made to provide a semi-solid or spongecathode for electric discharge devices, and the present inventioncontemplates improvement thereover.

In the broad aspect of the invention, more stable and unfailing arcdischarge is an objective and accomplished result thereof.

The invention also provides for more certain supply of the mercury orother reconstructive cathode material to the surface where the arc isinstigated.

A further object of the invention is to provide a cathode body notreadily poisoned during fabrication and/or operation of the ignitron.

Another object of the invention is to provide a cathode body of acharacter not affected adversely by standby periods and which willresume operation at any time desired without missing.

Other objects of the invention will appear to those skilled in the artto which the invention appertains as the description proceeds, both bydirect reference thereto and by implication from the context.

Referring to the accompanying drawing, in which like numerals ofreference indicate the same parts in both views thereof:

Fig. 1 is a central longitudinal sectional view of an ignitron ofarbitrarily selected construction showing my invention embodied therein;and

Fig. 2 is a cross-section on line lI-II of Fig. 1.

In the specific embodiment of the invention and associated ignitronconstruction illustrated in the drawing, but without limiting to thedetails thereof, a cylindrical casing I of steel or other sturdymaterial is shown having a bottom 12 integral therewith and a top headerI3 sealed at the upper rim of said casing to provide a closed envelopeadapted to be evacuated.

The particular header shown, provides appropriate lead-in seals l4, 5for electrode leads l6, l1 respectively for an anode I3 and ignitor 19within the casing and supported from said header by said leads. Thelead-in seals each include a glass or other insulating sleeve 20 bywhich the leads are kept electrically distinct from each other and fromthe casing. The anode I8 is located toward the top of the casing, wellabove the bottom wall l2, whereas the ignitor I9 is located below theanode, prefer-ably centrally of the casing, and is directed toward andterminates at its bottom in the vicinity of said bottom wall. Saidignitor is shown as relatively slender and tapers downwardly, with itsbottom end quite small. Said ignitor may be composed of materials asused for ignitors of the prior art. or may be of such other material ormaterials adapting it more especially to the present invention.

A sponge cathode, designated generally by'numeral 2|, is provided insaid container and is of pan-cake shape, and situated upon the bottomwall 12 of the ignitron, preferably fitting the container at itsperiphery and frictionally or otherwise held permanently in fixedposition. The aforementioned lower small end of the isnitor l9 restsupon the upper surface of the sponge cathode 2| in constant contacttherewith, and as one means for maintaining such contact withoutdetriment to the lead-in seal I5, the leadin I! for the ignitor, betweenthe seal and the ignitor, is shown with a transversely extending section22 which, with the rest of said lead-in, possesses adequate resiliency,supplemented by the weight of.the ignitor, to accomplish the purpose.The ignitor projects, from its contact on the sponge cathode, at rightangles thereto and in a direction longitudinally of the casing. Mercuryor other reconstructing liquid cathode material is applied to the spongecathode 2| to the extent that said sponge will absorb the mercury or thelike without any excess remaining on the surface. One manner of thuscharging the sponge body with mercury is to cleanse the sponge materialuntil sufficiently clean to be wetted by mercury and then apply anexcessive amount of mercury in the casing, whereupon the sponge willimmediately fill with mercury, after which the free mercury which is notabsorbed into the sponge can be poured oiT. The sponge cathode 2|, withthe absorbed mercury, constitutes the cathode of the ignitron.

According to the present invention, the sponge cathode 2| is constructedessentially of two different materials, of which one is usedto takeadvantage of its relatively large interstices between granules forproviding generous reservoir capacity, and also to take advantage of itscharacteristic of ailinity for and absorption of the mercury coming incontact therewith. Selection of the other essential material toconstitute the sponge cathode is for purposes of providing anarc-strikin surface generously supplied by capillarity through saidmaterial with mercury or the like, and to take advantage of resistanceof this other sponge material to contamination or poisoning thereofduring either fabrication procedure or during operation. Morespecifically, the present invention proposes for cathode 2| use of abody portion 23 essentially of sintered iron or other material havinghigh absorptive afiinity for the reconstructing cathode fluid, such asthe cury above mentioned, and an arc-striking portion 24 essentially asintered metal of the platinum group of elements. Both platinum andruthenium have proven to be excellent metals of this group for thepurpose, and of these, I select ruthenium as preferable. I havediscovered that these platinum group metals, and ruthenium inparticular, are exceptionally well suited as arestriking materials, asthey are easily wetted by mercury; show no adverse effects, mechanicalor chemical, from use with or from components of the usual ignitorgenerally employed in ignitrons; possess noteworthy smooth operation;and exhibit little, if any, evidence of sputtering in use in theignitron. A further and highly important advantage of use of the metalsof the platinum group, with emphasis on the use of ruthenium as thepreferred material, is that, even after long stand-by periods orintervals of non-use of the ignitron, there is no skipping or missing ofthe arc in striking instantly and invariably as required, and which isone of the drawbacks of molybdenum previously proposed in the art for acathode material.

In the specific disclosure arbitrarily selected for illustration in thedrawing, the bod portion 23 of the sponge cathode is shown relativelyflat or thin, of pan-cake shape to fit within the bottom portion of thecontainer fiatwise on the bottom wall thereof and frictionally orotherwise held fixed in that position. The arc-striking portion 24 isshown as a smaller disc than said body portion and embedded thereinconcentric thereto and according to the present illustration the upperfaces of the said body portion and arc-striking portion are in a commonplane. The arcstrikin portion is thinner than the body portion so that apart of said body portion underlies the arc-striking portion andprovides a copious supply of mercury or the like to said arcstrikingportion and by capillary action through the arc-striking portion themercury is ever present at the arc-striking surface. As the ruthenium,or its equivalent from the platinum group, has the beneficialcharacteristic of not drying up or of becoming non-wettable by mercury,the result is obtained of mercury always being present at thearc-striking surface and being invariably in condition for arc-strikingcontinuously, repetitiously,or-occasionally as desired or required.

Finally, it may be pointed out that the body portion 23 of compressedsintered granules essentially iron, is employed in conjunction with thecentrally disposed arc-striking portion 24 of compressed sinteredgranules essentially of the platinum group metal, to take advantage ofthe inherent characteristic of the iron sponge of more active absorptionof mercury coming in contact therewith than would occur with a similarlycompressed sintered body of metal of the platinum group. In view of thehigh cost of metals of the platinum group, the selected metal, in powderform, may be mixed with a less expensive metal or non-metal, also inpowder form, to serve as a filler, and such metals as molybdenum andtungsten and non-metals such as ceramics, may thus be employed to helpobtain desired volume or dimensions of the arc-striking portion 24, butwith said portion still essentially metal of the platinum group .Thepowder employed, whether soleis a platinum group metal or a mechanicalmixture with other materials, is compressed and sintered and juxtaposedto the body portion 23, which likewise, while preferably a compressedand sintered iron sponge, may be a mechanical mixture of which ironconstitutes the essential ingredient.

An ignitron in use will condense mercury vapor on the side walls of thecontainer, and that condensation forms in drops which run down the walland lodge upon the sponge cathode surface. By the provision of a spongeof sintered iron or the like in the vicinity of the side wall of thecontainer, said surface will be in appropriate location to receive andabsorb the drops of mercury and thereby avoid flow of mercury over thecen tral arc-striking surface portion. That mercury is delivered back tothe arc-striking portion 24 to the upper surface thereof and thusrepetitiously used. The arc-striking portion composed essentially ofruthenium or the like, is inherently closer grained and has smallerinterstices than in the iron or other sponge material of the bodyportion, and has the desired characteristic of rapid transition bycapillarity of the mercury copiously fed thereto by the sponge bodyportion.

I claim:

1. A vapor-electric device comprising a sealed container havin an anodetherein, a sponge cathode fixed in said container, said sponge cathodecomprising a sponge material receptive of condensed cathode materialflowing thereto down the side wall of the container, and an arc-strikingportion spaced away from said side wall and juxtaposed to said spongematerial, said arc-striking portion having an arc-striking surfaceessentially of a metal of the platinum group, an ignitor in said casingin contact with said arcstriking surface, and reconstructing cathodematerial absorbed in said sponge material.

2. A vapor-electric device comprising a sealed container having an anodetherein, a sponge cathode fixed in said container, said sponge cathodecomprising a sponge body portion and a sponge arc-striking portionjuxtaposed to the body portion, said arc-striking portion having anarc-striking surface essentially of ruthenium, an ignitor in said casingin contact with said arcstriking surface, and reconstructing cathodematerial absorbed and constantly present in said sponge cathode.

3. A sponge cathode for a vapor-electric device, comprising a bodyportion characterized by affinity to absorption of a reconstructingcathode material, and an arc-striking portion juxtaposed to the bodyportion and composed essentially of a metal of the platinum group.

4.. A sponge cathode for a vapor-electric device, comprising a bodyportion characterized by affinity to absorption of a reconstructioncathode material, and an arc-striking portion essentially of rutheniumjuxtaposed to the body portion.

5. A sponge cathode for a vapor-electric device, comprising a bodyportion characterized by aflinity to absorption of a reconstructingcathode material, and an arc-striking portion essentially of platinumjuxtaposed to the body portion.

6. A sponge cathode for a vapor-electric device, comprising a bodyportion characterized by affinity to absorption of a reconstructingcathode material, and an arc-striking portion essentially of compressedgranules of sintered metal of the platinum group.

7. A sponge cathode for a vapor-electric device, comprisin juxtaposedportions of difierent sponge materials of which the material for one 5 6of said portions is essentially a. metal of the UNITED STATES PATENTSplatinum group. Number Name Date 2,128,861 Tonks Aug. so, 1938 GERHARD 52,169,032 Slepian Aug. 8, 19 9 2,218,386 Smith Oct. 15,4240 REFERENCESCITED 2,432,513 Depew Dec. 1e,-;-1947* The following references are ofrecord in the 2,463,037 Clark Apr. 26.11949 file. of this patent: f

1. A VAPOR-ELECTRIC DEVICE COMPRISING A SEALED CONTAINER HAVING AN ANODETHEREIN, A SPONGE CATHODE FIXED IN SAID CONTAINER, SAID SPONGE CATHODECOMPRISING A SPONGE MATERIAL RECEPTIVE OF CONDENSED CATHODE MATERIALFLOWING THERETO DOWN THE SIDE WALL OF THE CONTAINER, AND AN ARC-STRIKINGPORTION SPACED AWAY FROM SAID SIDE WALL AND JUXTAPOSED TO SAID SPONGEMATERIAL, SAID ARC-STRIK-